Conventionally, bolts are arranged at appropriate portions of a covering member and a tightening means is executed while interposing a gasket attached around the covering member between the mounting portion and the bolt, thereby enabling to attach and fix the covering member such as the rocker cover and the oil pan of the engine to the mounting portion. Washer seal (metal annular gasket) having elasticity is interposed between the tightening means and the covering member in order to achieve sealing around the tightening means and sound and vibration control of the covering member. When the sensors like a pressure sensor and a temperature sensor are fitted on a mounting portion, a similar washer seal is interposed between a fitting male screw and a sensor housing in order to achieve vibration control of the sensors.
Such a washer seal is sometimes conveyed and transported while the neck portion of bolt and male screw (generically referred to tightening means hereinafter) is preliminary inserted into the inner hole (hole of tightening means). In such a case, if the tightening means is simply inserted into the inner hole of the washer seal, it sometimes falls down during conveyance and transportation, so that a rib is formed in the inner hole or a caulking deformation process is executed for the inner hole in order to prevent dropout. However, such a dropout prevention process requires an extra process during production of a washer seal, and sometimes damages the neck portion and screw portion of the tightening means. The Patent Document 1 and the Patent Document 2 disclose a washer seal (seal metal washer) wherein an inner hole to be inserted by the tightening means has a sealing portion made of rubber or synthetic resin so as to be elastically held with the inserted tightening means.
Patent Document 1 Japanese Utility Model Publication 6-82424-U1
Patent Document 2 Japanese Utility Model Publication 7-32218-U1